[PATCH] Add 'precision' to grub_printf %s format

[Christian Franke]

This patch adds 'precision' support to grub_printf '%s' format, e.g.:

grub_printf("data=%.20s...\n", data);

This feature of standard printf() is useful to limit output length or to 
print strings which are not 0-terminated.

Christian


2009-01-21  Christian Franke  <address@hidden> 

        * kern/misc.c (grub_vsprintf): Fix size and termination of `format2'
        (precision) digit string.  Allow `.format2' without `format1' (width).
        Limit input chars for `%s' output to `format2' if specified.  This is
        compatible with standard printf ().


diff --git a/kern/misc.c b/kern/misc.c
index 6fbc651..da64eb0 100644
--- a/kern/misc.c
+++ b/kern/misc.c
@@ -700,7 +700,7 @@ grub_vsprintf (char *str, const char *fmt, va_list args)
          char tmp[32];
          char *p;
          unsigned int format1 = 0;
-         unsigned int format2 = 3;
+         unsigned int format2 = ~ 0U;
          char zerofill = ' ';
          int rightfill = 0;
          int n;
@@ -727,20 +727,22 @@ grub_vsprintf (char *str, const char *fmt, va_list args)
                zerofill = '0';
              format1 = grub_strtoul (s, 0, 10);
              fmt = p;
-             if (*p && *p == '.')
+           }
+
+         if (*p && *p == '.')
+           {
+             p++;
+             fmt++;
+             while (*p && grub_isdigit (*p))
+               p++;
+
+             if (p > fmt)
                {
-                 p++;
-                 fmt++;
-                 while (*p && grub_isdigit (*p))
-                   p++;
-                 
-                 if (p > fmt)
-                   {
-                     char fstr[p - fmt];
-                     grub_strncpy (fstr, fmt, p - fmt);
-                     format2 = grub_strtoul (fstr, 0, 10);
-                     fmt = p;
-                   }
+                 char fstr[p - fmt + 1];
+                 grub_strncpy (fstr, fmt, p - fmt);
+                 fstr[p - fmt] = 0;
+                 format2 = grub_strtoul (fstr, 0, 10);
+                 fmt = p;
                }
            }
 
@@ -847,13 +849,19 @@ grub_vsprintf (char *str, const char *fmt, va_list args)
              p = va_arg (args, char *);
              if (p)
                {
-                 if (!rightfill && grub_strlen (p) < format1)
-                   write_fill (zerofill, format1 - grub_strlen (p));
-                 
-                 write_str (p);
-                 
-                 if (rightfill && grub_strlen (p) < format1)
-                   write_fill (zerofill, format1 - grub_strlen (p));
+                 grub_size_t len = 0;
+                 while (len < format2 && p[len])
+                   len++;
+
+                 if (!rightfill && len < format1)
+                   write_fill (zerofill, format1 - len);
+
+                 grub_size_t i;
+                 for (i = 0; i < len; i++)
+                   write_char (*p++);
+
+                 if (rightfill && len < format1)
+                   write_fill (zerofill, format1 - len);
                }
              else
                write_str ("(null)");